It's worth noting that Model F ATs have become super cheap now.
Any serious keyboard collector should own a Model F, and the AT is the one that has very few "problems" for utility in the real world.
If you don't have it, and can nab one for <$100, you should pounce on it while you can.
I should build a Soarer converter... I have 3 Model Fs inbound....
EDIT: 122-key Model Fs that is.
Where'd you get 122 key Fs?
Lot's of searching, finding the correct listing and getting my CC stolen (not really) by dodgy chinese sellers

In that same buy batch, I also got a Black M13 for under 25$ shipped to my contact in HK. Admittedly it's missing the "-" cap on the numpad (from the pictures. Seller may have just removed it for taking pictures of the spring), but I can replace that fairly easily.
My whole order came out to under $200 for three 122-key Fs, a black M13 and a compact ThinkPad-style keyboard+trackpoint (SK-8855 for the curious).
Now to find a cheap industrial SSK M....